1. Technical Field
The present invention relates to a board, more specifically to a noise reduction board that can reduce an EMI noise by use of an electromagnetic bandgap structure.
2. Description of the Related Art
As the operating frequencies of electric products become higher, electromagnetic interference (EMI) has been perceived as a chronic noise problem. Particularly, the operating frequencies of electric products have reached a few ten megahertzs (MHz), or even a few gigahertzs (GHz), making the EMI problems more serious. Subsequently, finding a solution to the problems is desperately needed. Among the EMI problems occurring at a board, a solution for the noise problems particularly occurred at the edge of the board has not been researched yet, making it difficult to completely shield the noise at the board.
EMI noise refers to a noise that generates a noise problem caused by an interference when an electromagnetic (EM) wave generated in one electrical circuit, component or part is transferred to another electrical circuit, component or part. The EMI noise can be broadly categorized into two types, namely radiation noise (reference numerals 110 and 130 in FIG. 1) and conduction noise (reference numeral 120 in FIG. 1).
The radiation noise 110, which is radiated towards an upper side of the board (that is, the mounting surface of an electronic part), may be commonly shielded by covering an upper portion of the board by use of an electromagnetic shielding cap, for example, a metal cap. However, few studies are trying to find an effective solution for the radiation noise 130 (hereinafter, referred to as an “edge noise”), which is radiated towards the outside of the board when a conduction noise 120 inside the board is conducted to the edge of the board.
If a technology is developed to reduce the edge noise at the edge of the board through a simple modification of the board structure, it is expected to significantly reduce the development time and costs, compared to the conventional method, which solves the problem through the use of a metal cap or a circuit. Additionally, such technology can have more merits in terms of space utilization and power consumption, and can easily remove a noise in a frequency band of a few gigahertzs (GHz), making it effective in solving the EMI noise problem at the edge of the board.